Due to many factors including the high cost of labor associated with populating circuit boards with components, technology in the electronic manufacturing arts has development to automatically place such components on boards. A representative system is seen depicted in U.S. Pat. No. 4,202,092. Tapes or magazines carry a plurality of components each of which is sequentially withdrawn from the tape or magazine. The pins thereof are then automatically inserted in corresponding holes in the board by means of a relatively complex mechanical robot arm linkage associated with each component type. Such systems are deficient in many respects. First, mechanisms were required to sever each component from the tape and bend leads for registration in the holes. Moreover, a complex mechanical linkage was required for each such component type as well as a corresponding relatively long travel path of the component from the tape or magazine to the location on the board. However, due to relatively small component densities, pin-in-hole tolerances initially in the development of the art were not so critical as to require more precise component placement.
Yet another example of the aforementioned art may be seen in U.S. Pat. No. 4,543,713 wherein there is disclosed yet another automated technique for installing components on a circuit board. A magazine containing a plurality of the leaded components is provided. In like manner to the hereinbefore noted reference, a relatively complex and large mechanical system is required for sequentially placing the components on the board. The system is primarily applicable to relatively large leaded components. Moreover due to the aforementioned relative complexity of the mechanical system involved, the number of systems and thus components which may be simultaneously placed on a single board is accordingly limited.
In U.S Pat. No. 4,222,166 disclosed therein is a system which seeks to alleviate some of the aforementioned problems. A plurality of pinned components are positioned proximate their appropriate positions on the board for subsequent manual insertion. A somewhat less complex mechanism is thereby provided so as to facilitate positioning of the components. The system nevertheless requires a manual step. Each component is sequentially withdrawn from its correlative magazine followed by manual insertion of the leads thereof in corresponding holes disposed through the board. Moreover, notwithstanding simplification of the mechanical system relative to the previously described references, the mechanisms were nevertheless still relatively complex and bulky.
In U.S. Pat. No. 4,528,747, a system is disclosed wherein sequential manual insertion of pins is sought to be avoided. A template is provided having a plurality of apertures for matingly receiving a corresponding plurality of desired components, although the reference provides little information as to how these components are loaded from corresponding magazines into the apertures. The template carrying the components is thence positioned over the circuit board by a robotic arm. By means of vibration, the pins of the various components are disposed through the appropriate holes. Not only does such a system require again a relatively complex mechanical system in the form of a robotic arm to position the components adjacent the desired sites on the circuit boards, but no details are disclosed for conveying the components from their respective magazines to their apertures in the template.
U.S. Pat. No. 4,300,715 reflects a move in the art to leadless components to avoid the aforementioned problems in placement of pinned or leaded components through circuit board holes. Component chips disposed on tape such as that used in the prior references to carry leaded components are removed from the tape sequentially by a complex robot gripper mechanism and deposited at the desired location on a substrate. In U.S. Pat. No. 4,342,090 there is disclosed a system for simultaneously positioning a plurality of chips onto corresponding sites. The chips are simultaneously withdrawn from their corresponding magazines and transported by means of a vacuum pencil pickup assembly travelling upwards, laterally, and thence downwards so as to deposit the chips on their respective sites.
In U.S. Pat. No. 4,451,324, yet another system is disclosed for depositing a plurality of chip type circuit elements on a board. A plurality of pipes are provided each of which extends to a supply of circuit components. The components travel through their respective supplies in an end-on-end fashion until they are deposited by the pipes at corresponding desired preselected locations on the circuit board. Elaborate boots and shuttle plate means are provided for thence rotating the components into horizontal alignment at desired orientations on a template whereupon the template thence deposits the various components simultaneously on the board in the desired alignment. There is no detailed disclosure of the means by which the components associated with each tube are individually disposed within each tube from the corresponding component supplies. Although a system is nevertheless disclosed for simultaneous chip placement, once again the mechanism in its entirety for positioning a plurality of chips adjacent corresponding circuit board sites is quite complex.
In a move to simplify the simultaneous positioning of chips adjacent correlative sites of a circuit board, a system is provided by Panasonic National, details of a representative system thereof being set forth in a publication entitled "Specifications: Panasert Simultaneous Chip Component Placement Machine Model No. NM-8270". With regard to such disclosure and specifically with respect to the details thereof set forth on page 8, a plurality of sticks each carrying stacked chip components therein may be loaded directly onto corresponding placement stations within the machine. The circuit board to be populated is thence positioned over the plurality of component sticks. The sticks are arranged in a horizontal pattern corresponding to the horizontal pattern of sites on the underneath side of the board at which the components are desirably to be placed. The underneath side of the board is coated with an adhesive. Upon upward urging of the stacks of components within their corresponding sticks by means of pushing pins or the like, the topmost components of the sticks are thereby urged against the adhesive on the board at the corresponding locations thereon where the components are desired to be placed. The thus-populated board is then replaced with the next board and the process repeated, resulting in simultaneous multiple chip component placement.
While the aforementioned system does eliminate problems associated with robotic arms, relatively complex travel paths of the circuit components from the magazines or tapes to the circuit board sites, and the like, several serious problems are nevertheless associated with this system. Notable among these are the tendency which components have to stick together when withdrawn vertically from the sticks caused by static, dust, dirt, adhesive or other particulate matter present on the components and adjacent thereto. Problems associated with this failure of components to uniformly exit the stick and be deposited on the board include jamming of the system and incorrect orientation of the uppermost chips in the stick after deposition on the board in undesired orientations (as, for example, when the chip may be turned so as to rest vertically on its edge rather than presenting a substantially horizontal planar surface to be impressed into the adhesive coating). This, in turn results, in unacceptable rejection rates for the populated boards. However, yet a further short coming of the apparatus was failure to provide a simple means for identifying the precise location of the jam or other malfunction as well as a means for preventing or minimizing the damage to the apparatus resulting from such malfunction.
In U.S. Pat. No. 4,393,579 still another system is disclosed for placing chips one at a time sequentially on a board. While the placement is from the top of the board and includes a shuttling mechanism for stripping single components from a magazine, and thence supporting and placing them by means of a vacuum support, the apparatus is extremely complicated and does not even remotely suggest replication of the entire apparatus many times over to effect simultaneous placement of a plurality of chips as in the case of the subject invention. Specifically, the apparatus calls for the mounting head to be secured on a table by means of a side wall so as to be adjustable in the X-Y direction. In this manner, a sequence of components may be placed on a given substrate one at a time by relocating the X-Y position of the placement head each time a next chip is sequentially placed on the substrate. This in turn gives rise to added cost and complexity in providing such mechanically orienting linkages as well as associated notorious inaccuracies with such systems and the inherent serious drawbacks of single chip placement.
Accordingly, a chip positioning apparatus adapted for simultaneous multi-component placement was desired which was of a small, simple, inexpensive and reliable construction for populating high circuit density boards. Such apparatus was further desired which also facilitated rapid off-line replenishment of chip supplies and ease of varying chip placement patterns to accommodate different product circuit boards and to minimize placement machine downtime.